main(List<String> args) {
  print("hello world");
  foo1();
  foo2().then((value) => print('foo2 value=$value'));
  foo3();
}

Future foo1() async {
  print('foo1');
}

Future<int> foo2() async {
  print('foo2');
  await Future.delayed(Duration(seconds: 2));
  return 1;
}

void foo3() {
  print('foo3');
}
